The instant invention is directed to a hoist assembly for use primarily with automotive machines, such as automobiles, trucks, tractors, etc. for lifting, moving and positioning motors and transmissions during automotive repair or assembly.
Hoist assemblies are well known as is illustrated by U.S. Pat. Nos. 4,144,973; 5,203,540; 5,897,100. Each of these devices include a vertical frame provided for floor movement, a vertical support and a boom. Each also includes a hydraulic drive for raising and lowering the boom.
It has been found that hydraulic drives are not reliable, cannot be controlled to finely adjust the position of the boom and are unsafe due to a tendency to xe2x80x9cdropxe2x80x9d.
The instant invention has as a primary object a hoist assembly in which the boom may be easily and precisely located in a selected vertical position.
Another object of the invention is a hoist assembly in which the boom will remain in its selected position until moved.
Another object of the invention is a hoist assembly in which the boom length is adjustable to precise selected positions.
Another object of the invention is a boom crank assembly for driving and maintaining the boom in selected adjusted positions.
Another object of the invention is a boom crank assembly which moves the boom position at a rapid rate.
Another object of the position is a multi-directional crank assembly for use with a hoist assembly.
The instant invention is directed to a hoist assembly and a crank assembly utilized therewith. The crank assembly comprises an elongated hollow housing with first and second elongated movable elements slidably mounted within opposed ends thereof. The outer ends of the movable elements carry a mounting assembly while the inner ends of the movable elements have a block secured thereto. Each block has a tap thread formed through its center. A crank mechanism is carried within the hollow housing and includes an elongated rod having a substantially centrally located driving area having left hand threads formed along a first section, right hand threads formed along a second section and at least one drive gear arranged between the threads. The left and right hand threads are engaged with the respective block tap threads of the first and second movable elements. A hand driven crank handle is connected with the crank mechanism for rotating the drive gear which causes the crank mechanism to move the movable elements in opposed directions at equal rates.
The crank mechanism includes a crank arm carried in a bearing which is secured with the housing and a gear which engages with the drive gear. A cradle is secured with an inner wall of the housing and includes at least one bearing adjacent the drive gear which supports the rod for rotation. The cradle is secured with an inner surface of the housing.
The hoist assembly includes a base, a vertical arm carried by the base, and a generally horizontally extending boom pivotally carried adjacent one end by the upper end of the vertical arm. The boom includes a boom extension arm extending from its opposite end.
A crank assembly, having opposed movable elements respectively connected to one of the boom and the vertical arm, is provided. The crank assembly is adapted to move the boom along a vertical plane and about the pivotal mount.
The boom comprises an elongated hollow housing in which the boom extension is reciprocally mounted. The boom crank mechanism is operative to selectively position the boom extension longitudinally of the boom. The boom crank mechanism includes a crank arm extending from one end of the boom.
There are a plurality of connections longitudinally of the boom for connecting a movable element with the boom.
The base of the boom assembly includes a brace for stabilizing the vertical arm in a vertical position. The base includes a plurality of horizontal arms extending radially from the vertical arm. Each of the horizontal arms mounts a rotatable caster at its end remote the vertical arm allowing multi-directional movement of the assembly. Also, the horizontal arms are longitudinally adjustable providing addition stability when required.
Preferably the base, the vertical arm, the housing, the boom and boom extension are formed of rectangular hollow tubing.